THERMAL QUENCHING OF FLUORESCENCE IN CHROMIUM-DOPED FLUORIDE LASER CRYSTALS

The temperature dependence of the fluorescence lifetime of chromium ions in the fluorides LiBaAlF6, LiCaAlF6, LiSrAlF6, and LiSr0.8Ca0.2AlF6 is reported. In each crystal the lifetime at low temperatures is nearly constant. Above a temperature that depends on the host the lifetime drops rapidly with increasing temperature. This strong decrease is attributed to nonradiative decay processes. From the experimental data the radiative decay rate, the thermal quenching activation energy, and the nonradiative decay rate are determined. Excellent agreement with the Mott model is then demonstrated by using these parameters.